Super Typhoon Hagibis has ramped back up to Category 5 intensity after weakening slightly Tuesday as it built a new ring of intense thunderstorms surrounding its eye.
The storm, featuring maximum sustained winds estimated at 160 mph as of Wednesday morning, is forecast to maintain its current Category 5 status for much of Wednesday before beginning a slow weakening trend as it curves more to the north and eventually northeast. Ultimately it moves toward a close encounter with, and possibly a direct hit on, the heavily populated main Japanese island of Honshu.
While the current forecast track could change given uncertainties this far in advance, it has the storm moving directly over Tokyo on Oct. 12. By that point, cooler ocean waters and disruptive upper atmospheric winds will likely have weakened Hagibis — which means “speed” or “velocity” in Tagalog — to a Category 2 storm.
Where Hagibis has been and where it is headed
Super Typhoon Hagibis is large, with an eye measuring 35 miles across that is surrounded by towering thunderstorms comprising what is known as a central dense overcast, or CDO, which is a sign of a particularly powerful storm.
The storm’s satellite presentation is considerably different from earlier this week, when it had a pinhole-sized eye that was five miles across or even smaller at times. Given the increase in eye size, strong winds are now more spread out. As you can see in satellite imagery, the storm now closely resembles a doughnut.
This transformation resulted from a process known as an eyewall replacement cycle. This phenomenon takes place in many mature tropical cyclones. It occurs when the eyewall, or ring of most intense thunderstorms containing the storm’s peak winds and heaviest rains, breaks down, and is replaced by a new and often larger eyewall. Sometimes, storms emerge from the process stronger, and frequently with a larger wind field.
As Super Typhoon Hagibis moves farther north and begins to weaken, its wind field is likely to expand, making storm surge flooding, heavy rain and inland flooding, mudslides and high winds major threats for much of Honshu if it passes very close to or over the island. A track farther off the coast would lessen the impacts.
Hagibis has been the equivalent of a major hurricane (Category 3 or above) since Sunday night and a Category 4 or 5 storm since early Monday eastern time.
The storm underwent one of the fastest rates of intensification ever observed from Sunday to Monday, when its maximum sustained winds increased by 100 mph in just 24 hours.
According to Colorado State University hurricane researcher Philip Klotzbach, the storm has now been a super typhoon, with maximum sustained winds of 150 mph or greater, for at least 36 hours. This is a record in the Western North Pacific Ocean so far this season.
This Western Pacific Ocean typically spawns some of the most intense tropical cyclones of any place on Earth, although storm activity has been somewhat suppressed this year.
Global warming may favor rapid intensification
One way scientists think global warming will affect tropical cyclones is by enabling more of them to reach the higher end of the scales, such as Category 4 or 5 intensity, and to do so through rapid intensification. There is evidence that rapidly intensifying storms are already becoming more common in the North Atlantic Ocean, for example.
A 2017 study that examined modeled Atlantic storms showed an uptick in the number of storms that would rapidly intensify just before landfall in a warmer world.
Another study, published in 2018, found that with continued global warming, more tropical cyclones are likely to undergo rapid intensification than in the past. It also found, using a climate model capable of simulating these massive storms amid changing atmospheric and oceanic conditions, that future storms could be so intense that a new category — Category 6 — might be required to describe their intensity.
For the period between 2016 and 2035, the study found there would be an 11 percent uptick in major tropical cyclones, of Category 3 intensity or greater. It also showed 72 storms with maximum sustained winds above 190 mph by the end of the century, compared with just nine such storms in a simulation of the late-20th-century climate.